Sima Yue

Sima Yue (died 311) was the regent of the Jin dynasty from 307 to 311, the last of the princes in the War of the Eight Princes. Known as the "Prince of Donghai", he seized power from Sima Yong after fighting in the feuds for the title of regent.

Biography
Sima Yue was the grandson of a brother of Sima Yi, and he was the cousin of the founder of the Jin dynasty, Sima Yan. In 291 he was made Prince of Donghai by his cousin, and he was given government posts under his cousins when they ruled China. During the War of the Eight Princes, Sima Yue served Sima Ying and turned over Sima Ai to the anti-Sima Ai coalition, leading to Sima Ai being executed. Sima Yue later rebelled against the unpopular Sima Ying, with more people uniting behind him due to his hatred of Sima Yong's general Zhang Fang, who was the executioner of Sima Ai and a person known for his cruelty. In 306 Sima Yue won small victories against Sima Yong, who executed Zhang Fang in hopes of reconciliation with Sima Yue. However, Sima Yue refused, and he defeated him in battle. Later, he offered to give Sima Yong a government position, but while Yong was en route to take office, Yue's brother Sima Mo killed him. Sima Yue was now the regent, and he poisoned Emperor Sima Zhong so that he could place Sima Chi on the throne as "Emperor Huai of Jin" and his puppet.

In 309, when Emperor Huai was gaining power, Sima Yue had Huai's uncle and several of his retainers executed, and he replaced the imperial guard with his own troops to protect the emperor. However, Sima Yue was faced with attacks by the expanding Han Zhao dynasty, with Emperor Zhaowu of Han Zhao leading invasions of Jin. In 310, Huai was abandoned in Luoyang, which became a city overrun by bandits as the army left. An angered Huai plotted against Sima Yue, with Qing Province commander Xun Xi aiding him. Sima Yue was unable to fight Xun Xi, and he died of stress in 311.